Telephone system



3 Sheets-Sheet 2 H. HOVLAND TELEPHONE SYSTEM Filed April so. 1926 ply- 0 h m l h w my ML Q WNW M v m l m M W NEE v Q fiw m r 3w: K W W 5% Q. Eg v v NWN= N\N.

Oct. 4, 1927.

\9 H v V A \m3 3 N H. HOVLAND TELEPHONE SYSTEM Filed April 30. 1926 5 Sheets-Sheet 5 v mQQW Rub Patented Get. 4, 1927.

UNITED STATES v 1,644,060 PATENT OFFICE.

HENRY I-IOVLAND, OE FLUSHIN G, NEW YORK, ASSIGNOR TO BELL TELEPHONE LABORA- TORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF YORK.

TELEPHONE SYSTEM.

This invention relates to in'iprovements in telephone systems and particularly to selective switching arrangements for use in automatic telephone systems. v i

The principal ob'ect of this invent-ion is to enable the transfer of a permanent signal from a main ofiice selector to a local selector and the release of the main ofiice selector.

Another object is to remove, under control of the local trunk, the dialing bridge and condensers from the connection while dialing over said local trunk.

It has been the practice heretofore when a line in a satellite oilice became grounded to light a. signal in the main office selector which remained lighted until the trouble was cleared and the connection released thereby holding a trunk and selector in the main ofiice busy. It is also old in the art to remove a dialing bridge from a repeater.

By this invention the signal is transferred from the main office selector to a bypass repeater in the local ollice. The by-pass re-- peater then causes a lamp associated with itself to light and releases the main o'fice trunk and selector. The signal then remains lighted in the by-pass repeater until the trouble is cleared but does not hold the main oltice, trunk and selector busy. The dialing bridge is removed under control of the local selector when the call is transferred from the main ollice to the local ofiice thereby econo mixing in the use or apparatus.

The system disclosing the invention in, one of its limited embod ments consists of a calling subscribers line in a satellite or local ofice, a by-pass selector and repeater circuit, a trunk to a main otlice, a main office selector and a trunk from the by-pass selector to a local select-or in a local or satellite oI"- ties. The. by-pass selector is used for bypassing a call from one local subscriber to another local subscriber without involving the main ofiice. This feature is claimed in acopending application by E. Jacobsen, Serial. No. 107 ,7 55, filed May 8, 1926. \Yhen a call is initiated whether for a. local or main office subscriber, it is routed to a main olfice selector. Certain levels of this selector have battery and groundccnnected thereto and these levels are reached by the dialing of certain numbers which are ased to local oliice subscribers. The bats tery and ground connected to these levels operate a polarized relay in the by-pass selector which causes the release of the main oi'iice selector switch and initiates the selection of a trunk to a selector in a tributary 'ofllce. This leaves the main office selector tree for use by other by-pass repeaters.

If a line in the tributary oflice should become grounded, or the conductors be crossed the system will operate in the same manner as when a call is being initiated Withthe exceptlon that no number is dialed and a permanent signal will be given after a predetermined lapse of time in the first selector at the main oflice. This signal is received by an attendant in the mainoflice who shortcircults the trunk conductors thereby causlng the by-pass selector to release the trunk and light a similar. signal connected with the bypass repeater in the local oflice. A more. clear conception may be'obtained of the objects and operation of this invention from the following description in which:

Fig. 1 shows the bypass selector S with two sets of brushes, the upper set of which are connected to a selector in the main office and the lower connected to aselector in a local or satellite oflice.

Fig. 2 shows a second selector in a main office, the banks of which are, shown connected to a subscribers station in the main olfice and other banks to which battery and ground are connected for controlling the selector S. An alarm circuit and timing device is shown in the lower right hand corner.

Fig. 3 shows "a selector in a local office.

Fig. 4 is a diagrammatic representation of the system. A is a calling line, B the by-pass selector, B the main ofiice selector and C the main office line. E is the selector in the local office and the line from R to E designates the trunk from the by-pass selector to the local office selector E.

Fig. 5 illustrates the manner in which the different sheets of the drawing should be arouter left back contact of relay 106, brush."

and terminal 103 of line switch 102, through the subscribers loop .101, line switch 102,

' brush and terminal 104;, inner left back conthrough the outer right back contact of relay 7 213 and thence over the'same circuit through the winding of relay 213. While the brush- 212. is resting on a busy terminal relay 213 is shunted but, as'soon as an idle terminal is found, this shunt is removed and relay 213 operates and connects conductors 129, 139 and 149 through to brushes 210, 211 and 212. When the call is for a subscriber such as 301 in a local office, certain levels such as those containing terminals 203 and 204 corresponding to the first digit of the sub scribers number have battery and ground connected thereto for giving a battery reversal to the by-pass selector.

lVhen such a call is made the operation of the main ofiice selector switch'will be as follows. After the first digit is dialed and the rotary magnet 215 is operated brushes 210, 211 and 212 are caused to hunt. No ground will be found for brush 212 in this level, therefore relay 213 will operate as described above and close the conductors 129, 139 and 149 through to brushes 210, 211 and 212 which are assumed to be resting on terminals203 and 204. Batteryand ground will be connected to these terminals, and will clrre circuit from battery on terminal 203, brush'210, outer left front contact of relay 213, conductor 129, are and brush 120, outer right front contact of relay 111, left front contact of relay 107 through the polarized winding of relay 114, winding of relay 122, middle rigl'it front contact of relay 111, are and brush 130, conductor 139, inner right front contact of relay 213 to ground on terminal 204 through brush 211. Relays 114 and 122 operate. Belay 114 opens the circuit through relay 115- which is. slow-to-release and so holds up until a circuit'has' been closed for operating relay 113 from ground on the outer front contact of relay 114, frontcontact of relay 115 to battery through the winding of relay 113. The operation of relay 122 performs no function at this time but the windings of these relays form a repeater bridge to the main office. Relay 113 operates and locks over an obvious circuit to ground on the outer leftfront contact of relay 109. The operation of relay 113 closes a circuit from battery through the winding of magnet 116, outer left front contact of re- .allows them to release. The releaseof relay 213 closes a circuit from ground on its inner left back contact; back contact of relay 222, left back contact of relay 221,- lower alternate contact of off normal contact spring 224 to battery through the winding of relay magnet 214. The operation of release magnet 214 causes brushes 210, 211 and 212 to restore to normal thereby restoring the entire switch to normal.-

If the brushes of arcs 150, 160 and 170 are resting on a busytrunk, ground will be connected to brush 150 thereby closing a shunt around relay 106 through its right back cont-act to the outer left frontfcontact of relay 113. If relay 106 is shunted, magnet 116 will be operated thereby stepping brushes 150, 160 and 170 until an idle trunk is reached when the shunt around relay 106 is removed allowing it to operate. Magnet 116 does not operate at this time as the resistance of relay 106 is too high. The operation of relay 106 disconnect-s conductors 126 and 136 from terminals 103 and 104 and connects conductors 131, 132 and 133 to terminals 103, 104 and through the contacts of relay 106. hen conductors 126and 136 are disconnected from the terminals, the circuit for relay 107 also opens allowing it to release. in turn releasing relays 109 and 110. The release of relay removes the repeater bridge from across the main oflice trunk and the circuit is ready for direct dialmg. 7

Selector S is now in condition for the next digit to be dialed to the selector in the local ofliee over leads 169 and 179. A circuit is closed from ground through the left win ding of relay 322, outer right back contact of relay 313, conductor 179, brush and are 170, conductor 132, outer left front contact of relay 106, terminal and brush 103 of line switch 102, through the subscribers loop, brush and terminal 104, inner left front contact of relay 106, conductor 131, brush and till got:

are 160, conductor 169, innerleft back contact of. relay 313 to battery through the right windingof relay 322. Relay 322 follows the ialimpulses in the same manneras relay 222v and the operation of the circuit is the same as that described, for the selector in Fig. 2. It will be noted that the numbering of the apparatus of Fig. 3 is the same as that of Fig.2, with the exception'of the hundred digit.

After the brushes 307, 308 and 309 of the second selector have been positioned on the terminals of anidle trunk, the final selector switch FS is operated bysubsequent impulses to position its brushes 305 and 306 on the terminals 303 and 304, which are con nectedby connectors 302 to the called line.

l/Vhen subscriber 301 replaces the receiver on the switchhook, the release of the switches in Fig. 3' is the same as that described for the switches in Fig. 2 when released by the by-pass selector.

When a line in a satellite or local otiice is grounded or the leads are crossed selector S will operate as described above and select an idle main office trunk and first selector which will operate in the usual manner with the exception thatrelay 222 will not be perated and released by the operation of the dial. Therefore the circuit through relays 221 and 251 wil'be closed for an al'jnormal length of time. This period of time is determined by a timing mechanism consisting of magnets 256 and 257 With their respective switches 258 and 259. Magnet 256 is so adjusted that switch 258 will step one step every five seconds while magnet is so adjusted that switch 259 makes one step every thirty seconds. It is desirable when giving a signal concerning these two types of trouble to wait about five minutes, therefore the switch 259 is wired to give an impulse every five minutes.

lVhen relay 251 is operated a circuit is closed from ground on its right front con tact, left back contact of relay 2-52 to battery through the back contact and winding of magnet 256 thereby causing switch 258 to step in a well known manner. eration of switch258 operates relay 2541 over an obvious circuit at five second intervals. Relay 25% operated closes a circuit from battery on its front contact through the right winding and left back contact of relay 253, left back contact of relay 252 to ground on the right front contact of relay 251. Relay 253 operates and locks to the same ground through its left winding and left front contact. Magnet 257 has in the meantime been stepping switch 259 at the rate of one step each thirty seconds. 'After the elapse of five minutes the brush of switch 259 should be resting on terminal 10 and an obvious circuit is then closed for relay 255 which operates and closes a circuit from ground on its front contact, right front contact of relay 253 to battery throughthe winding of relay 252. Relay 252 operates and locks to ground on the rightv rout con-' tact of relay 251 and closes an, obvious. circuit for lighting lamp 260 This lamp is a signal to the attendant at the main office that a. line in a satellite oflice isin trouble. The

attendant then. inserts a plug in test jack 2-13 which short-circuits conductors 129- and 139 thereby releasing relays 11 1 and 122. The

release of. relay 122 closes a circuit frora battery through the winding ofrelay.112, inner left front contact ofrelay 111. back contact of relay 122, right back contact of relay 110, outer right front contact of Delay 109 to ground on the outer right ba k con is in trouble.

The op-' tact of relay 113. Relay 112 operates and locks to the same-ground through its inner left front contact. An obvious circuit is also closed for lamp 118 through its outer right front contact'as an indication that the line connected to selector S, such as line .101, 'lhe operation of relay 112 also opens a circuit for relay 111 releasing it and thereby opening the conductors to arcs 120, 130 and 1&0 thus disconnecting the trunk to the main office. Lamp 118 will remain lighted until the trouble is cleared and relay 107 .is released in turn releasing relay 109 which opens the locking circuit for relay 112. The by-pass selector S is then in condition for further use. I

W hat is claimed is:

1. In combination a local oliice, a sub scribers line, and an automatic switch in said local office, a main office trunk, a main ollice, a selector therein, a permanent signal in said selector to indicate an unstandard condition on said line, causing said line to be extended over said trunk to said selector, and means in said automatic switch for transferring said signal from the main office selector to said automatic switch.

2. In a. telephone system, a local office, a subscribers line, and a repeater in saidlocal oliice, a" main office trunk, a main office, a selector therein, a permanent signal in said selector to indicate an unstandard condition on said line, causing said line, repeater, trunk and selector to be interconnected, a". l means in said re eater for releasing said main ofiice trunk and selector and transferring said signal to said repeater. I

3. In a telephone system, a local office, a sub'scribers line, and a bypass repeater-in said local office, a main cities trunk, a main oflice, a selectortherein, a permanent signal in said selector to indicate an unstandard condition on said line, causing said line, repeater, trunk and selector to be intercon nected, and a relay in said repeater for causing the releaseof said main office trunk and selector.

l. In 'a telephone system, a local ollice, a subscribers line, and a repeater in said local office, a main office trunk, a main oliice, a selector therein, a permanent signal-in said selector to indicate an unstand'ard condi Inc tion on said line causing said line, repeater,

p ate nd au omat cally elective means i mechanism for driving all of said Wipers,

i a dialing bridge in said repeater, and a relay in said repeater for removing said bridge 1 when dialing over said local trunk.

In Witness whereof, I hereunto subscribe my name this 29th day of April, A. D. 1926.

HENRY HOVLAND. 

